JPH0779082A - IC mounting case - Google Patents

Abstract

(57) [Summary] [Purpose] Resin encapsulation with excellent mass productivity and low manufacturing cost I
(EN) Provided is an IC mounting housing that can be used when C has a high power consumption at high frequencies and has a high operating environment temperature. [Structure] A printed circuit board 1 is provided with conductive patterns 3 which are electrically connected to each other on the front and back surfaces of the printed circuit board 1 through a through hole 6, and a resin sealing IC 2 is provided on the front conductive pattern.
Implement. The housing covers 4 and 7 having the recesses 5 that press-contact the resin-sealed IC 2 mounted on the front surface of the printed board 1 and the conductor pattern 3 on the back of the printed board 1 absorb the heat of the resin-sealed IC 2 from above and below, The heat dissipation effect of the resin-sealed IC2 is promoted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing for mounting ICs, and particularly to a resin which is required to suppress temperature rise at high frequencies used in wireless communication devices and the like, and due to performance, reliability and quality restrictions. The present invention relates to an IC mounting housing for a sealed IC.

[0002]

2. Description of the Related Art A resin-encapsulated IC is superior to a packaged IC made of metal or ceramic in mass productivity and is inexpensive to manufacture, but the thermal conductivity of the resin material is lower than that of metal, and the heat radiation is The heat is conducted to the conductor pattern of the printed wiring circuit board on which the IC lead wire is mounted via the lead wire of the IC.

Therefore, in order to guarantee the reliability and the performance of the IC itself, the upper limit of the usable environmental temperature is restricted. In particular, in the high frequency band of VHF to SHF used for wireless communication and the like, since electromagnetic waves easily propagate in the air, it is necessary to install a high frequency circuit section including an IC in a metallic electromagnetic wave shielding case. is there.

On the other hand, for ICs, a surface mounting method is widely used for miniaturization, but most of the surface mounting ICs and other small parts are mounted by an automatic mounting method in view of workability and quality. It Therefore, labor cost is reduced by labor saving in the assembling process, and the size and cost are reduced.

Conventionally, surface mount type resin-encapsulated ICs have been difficult to be used for applications with high environmental operation at high frequencies, which generally consumes a large amount of power, due to heat dissipation problems.
Japanese Patent No. 32059 discloses a method in which a metal plate for heat radiation is attached to a resin-sealed surface of an IC, and heat is radiated by heat conduction to a casing component such as a conductor pattern of a circuit board and a metal cover.

In this method, as shown in FIG. 2, in addition to the heat radiation path from the IC lead terminal 10 to the conductor pattern 3 of the circuit board 1, a metal plate 12 is pressed against the resin sealing surface of the IC 2 and this metal plate is attached. While soldering to the ground conductor of the circuit board,
The heat dissipation is improved by contacting the housing cover 14 as well.

By connecting this metal plate to a ground conductor, radiation of high frequency electromagnetic waves is prevented. Further, the temperature rise due to the heat generation of the IC itself due to the contact with the housing cover 14 is suppressed by approaching the ambient temperature of the outside air. Therefore, it is premised that the housing temperature is closer to the environmental temperature than the IC. Further, the housing such as the cover is naturally grounded at a high frequency for the electromagnetic shielding function.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the method of mounting the IC disclosed in Japanese Patent Publication No. 9, since the metal plate pressed against the IC resin sealing surface is soldered to the ground conductor of the circuit board, the shape and structure of the metal plate are complicated and expensive.

Further, since it is extremely difficult to automatically mount the soldering work on the circuit board, it becomes a manual work and the same I
When a plurality of Cs are mounted, the labor-saving effect of surface mounting automatic mounting is significantly impaired.

Further, if it is premised that the cover can be opened and closed, it is difficult to reduce the contact thermal resistance, and the heat radiation effect to the cover is limited. Also, the number of ground leads of an IC is usually limited in view of the total number of input / output terminals of the IC, and although the ground conductor pattern can be improved in thermal conductivity by using a wide pattern for high frequency, only the ground conductor is used. The conductive heat dissipation used has a small effect of improving the total heat dissipation from the IC lead.

Further, conduction heat dissipation by providing a land for soldering a metal plate around the IC or arranging a grounding conductor pattern, if there are many power supply patterns and input / output line patterns supplied to the IC, patterns of the circuit board. There is a problem in that there are some restrictions on the design.

In particular, when the ground DC potential of the IC is independent of that of the housing, the heat dissipation effect of the ground conductor can hardly be expected, and this method cannot be used.

An object of the present invention is to allow a metal plate to be easily pressed against the IC resin sealing surface without deteriorating the labor-saving effect of automatic surface mounting of the IC, and the case cover can be detached and the resin can be removed. An object of the present invention is to provide an IC mounting housing that has a high heat conduction and heat dissipation effect from the sealed IC to the housing components.

[0014]

An IC mounting housing according to the present invention is a printed wiring board, front and back conductor patterns provided on both main surfaces of the board and electrically connected to each other, and the front conductor pattern. An IC mounting housing of an electronic device including an IC package mounted thereon, characterized by having a recess for sandwiching the IC package and a back conductor pattern and making pressure contact.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a housing according to an embodiment of the present invention.

A resin-sealed IC 2 is attached to the printed wiring board 1 with a conductor pattern 3 interposed therebetween, and an upper cover 4 is provided.
The upper surface of the resin-encapsulated IC 2 is in pressure contact with the recess 5 provided in the.

On the other hand, the conductor pattern 3 on the printed wiring board 1 sandwiched between the resin-sealed ICs 2 is the printed wiring board 1
It is pressed against the back surface of the printed wiring board 1 by the recess 5 provided in the lower cover 7 via the through hole 6 provided in the.

The upper cover 4 and the lower cover 7 are engaged with the projections 9 formed on the outer peripheral edge of the metal chassis 8 attached to the printed wiring board 1 to form a housing.

The heat generated by the resin-sealed IC 2 is conducted to the recess 5 of the upper cover 4 and propagated to the entire upper cover. Further, the heat under the resin-sealed IC 2 is transferred from the conductor pattern 3 between the resin-sealed IC 2 and the printed wiring board 1 through the through holes 6 provided in the printed wiring board 1 to the conductor on the back surface of the printed wiring board 1. Propagate to pattern 3, and
It reaches the recess 5 of the lower cover 7 and propagates to the entire lower cover 7.

The upper and lower covers are made of a metal material and are heat-treated, so that the upper portion of the resin-sealed IC 2 and the printed wiring board 1 are covered.
The conductor pattern 3 on the back surface is formed so as to have a spring property (elasticity) when being pressed.

The depressions 5 in the upper and lower covers can be formed by press forming using a folded portion 15 fixed to the protruding portion 9 of the outer peripheral metal chassis 8 and similarly using a die. Further, the upper and lower covers can be removed, and even if the number of mounted ICs is large, they can be manufactured by integral molding, so that there is almost no increase in cost due to the increase in the number of dents.

The signal conductor pattern 11 connected to the IC lead terminal 10 having the same potential as the ground potential of the housing is connected to the conductor pattern 3 which is pressed against the lower cover 7 by the through hole 6. Although it may have a heat dissipation effect, it is usually an IC with the same potential as the chassis ground potential.
Since the number of leads is small, the heat dissipation effect cannot be expected so much.

Further, silicon compounds may be applied to the upper and lower pressure contact portions, or a flexible sheet having a high thermal conductivity may be sandwiched.

[0025]

According to the present invention, it is possible to use a resin-sealed IC that consumes a high frequency and consumes a large amount of power, and to raise the operating environment temperature. There is an effect that labor saving can also be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional IC mounting example.

[Explanation of symbols]

 1 Printed Wiring Board 2 Resin Sealed IC 3 Conductor Pattern 4 Upper Cover 5 Recess 6 Through Hole 7 Lower Cover 8 Metal Chassis 9 Projection 10 IC Lead Terminal 11 Signal Conductor Pattern 15 Folded Back

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H05K 9/00 U

Claims (4)

[Claims] 1. An IC of an electronic device including a printed wiring board, front and back conductor patterns provided on both main surfaces of the board and electrically connected to each other, and an IC package mounted on the front conductor pattern. An IC mounting case, comprising a recess for sandwiching the IC package and a back conductor pattern and making pressure contact with each other. 2. The IC mounting housing according to claim 1, further comprising: a chassis frame body attached to the wiring board and having a protrusion on an outer peripheral edge portion thereof; and a cover which is engaged with the protrusion. 3. The cover includes a first cover member having a first recess that press-contacts a surface of the IC package, and a second cover member having a second recess that press-contacts the back surface conductor pattern.
The housing for mounting IC according to claim 2, comprising the cover member. 4. The IC mounting housing according to claim 3, wherein the cover member is made of an elastic material.